Dragees represent oral application forms of medicaments, i.e. cores obtained in any manner containing in suitable quantities the medicaments or pharmaceuticals, and provided with a coating, i.e. the dragee casing. Such coating can be used for various purposes. The surface of the dragee should thus be made smooth, so that it can be readily swallowed in which connection any unpleasant taste inherent in the medicament should possibly be masked. Further, the coating should improve the appearance of the dragee, distinguish it by means of color and, in many cases, exert an effect on the breaking up of the dragee core in the gastrointestinal tract, in particular retard the dissolving of the effective substances.
Such dragee coatings are often made especially of sugar composition which may contain dye and pigment additives, as well as film-forming agents. The coatings are applied from solutions in aqueous or organic solvents often in several layers by spraying such solutions, possibly in connection with the simultaneous addition of further pulverulent coating materials, on the tablets or dragee cores arranged in a rotating dragee-container or a fluidized-bed device, while blowing in warm air. As film-forming agents, there may be employed generally shellac, cellulose derivatives, such as cellulose acetate phthalate, as well as possibly substituted polymers of acrylic or methacrylic acid, in which connection such film-forming agents should provide some resistance to gastric juice and retard the release of the active substances.
The coating must provide an optimal seal in the case of unpleasantly tasting and strongly smelling active agents. The film-forming materials based on high-molecular substances which could as such provide a good seal, lead to a delay in the breaking up of the dragee, which is frequently undesirable. The use of such film-forming agents for the coating also represents an undesirable burdening of the patient, in particular in the case of such unpleasantly tasting or smelling medicaments, that must be taken in considerable amounts by patients and are thus applied generally in the form of microdragees, that can be swallowed more readily in large numbers and possess a diameter of 0.4-4mm, preferably at most 1.5-2mm. Such burdening of the patient takes place especially because the percentage of the film-forming polymers is relatively large in comparison with the active agent in the case of microdragees.
Although microdragees are particularly suitable for administering large amounts of badly tasting or smelling medicaments, such as essential amino acids or their keto and hydroxy analogs that must be dosed, e.g. in the amounts of about 15 to 20g per day in the case of uremia patients, no satisfactory industrial method of manufacture was possible until the present time. The solution of the problem failed especially on the fact that the processes and coating means known until the present for masking the taste and smell either exhibit unsatisfactory effects during the dragee-making or there are required excessive amounts of such coating materials, that are not desired as such, but must then be administered to the patient together with the active materials. Reactions may also take place between the coatings and the medicaments, that are frequently reactive and unpleasantly tasting and smelling, which reactions may occur during the manufacture of the dragees through the action of high temperature of drying or which result from the use of organic or aqueous solutions; such reactions may also introduce moisture and decomposition, which later comprise microbial decay. Coatings consisting of fat can be penetrated by lipophilic substances and can thus be used only to a limited extent.